David Hasselhoff was back on the "Baywatch" beach ... teachin' the youngins a thing or 2 about fake lifeguarding.
The 63-year-old showed up on the set Tuesday in Savannah, Georgia, giving pointers to The Rock on how to properly jog on the beach, before sitting down to enjoy a couple of ice cold beers.
The Hoff jawboned it with Zac Efron ... then took pics with a random couple who got married on the sand.
David's in the movie as the OG. Hard to do it without him.